These are some files to help you with mission creation. For a general guide on mission creation you can use this FSDeveloper wiki page.
The SimpleMission ZIP is a sample project for creating missions, like the ones you find in the SDK. This project is a good starting place for creating any mission, except for Bushtrips or LandingChallenges (for those you are better of just using BushMissionGen or BushTripInjector).
The instructions for the SimpleMission sample project are in this guide.